The present invention relates to a paint drying oven for a vehicle which uses a radiant energy floor and to a method of drying paint on a vehicle using a radiant energy floor.
Paint drying ovens are used on vehicle production lines. A vehicle body is initially transported through a paint spray booth where paint is applied to the body. The vehicle body is then transported into a paint drying oven. During the curing or drying process, the vehicle body is transported through the paint drying oven while drying energy is applied to the vehicle body to dry the wet paint. For the purpose of this invention, the term "drying" is used synonymously with "curing."
Various factors influence the selection, operation and design of paint drying ovens. The oven must apply drying or heat energy to the vehicle body, while at the same time not disturbing the wet paint finish on the vehicle body. Also, it is desirable to maintain the vehicle body in its entirety at a single target temperature during drying. Thus, while convection heaters, which blow heated air onto the vehicle, have many desirable attributes in maintaining a relatively constant vehicle temperature, they have undesirable characteristics due to the volume of air being directed onto the wet paint. However, the other major type of drying ovens, radiant ovens, have not always been able to uniformly apply drying energy to the vehicle. The prior art radiant ovens have used radiant generators on the side walls or ceiling of the oven. In most vehicle bodies, more heat needs to be directed towards the lower part of the body compared to the upper part of the vehicle body. The upper vehicle body, such as the vehicle roof, etc., is typically formed of thinner metal, and thus requires less heat.
A typical paint drying oven for a vehicle is divided into two sections. The first section, a so-called "heat-up" section, initially heats the vehicle body to a relatively hot target temperature. The particular target temperature depends upon the type of paint being applied, however, it is usually above 200.degree. F. In particular examples, for a primer paint oven target, temperatures of between 280.degree. F. and 330.degree. F. are achieved in the oven. For a color paint oven, target temperatures of between 250.degree. F. and 290.degree. F. are achieved. For an electro-coat oven, target temperatures of between 320.degree. F. and 400.degree. F. are achieved. Once the heat-up section has achieved this initial heating of the vehicle body, the vehicle body moves into a second portion typically known as a "hold" portion. In the hold portion, the vehicle is maintained at the target temperature achieved by the heat-up portion for a period sufficient to dry the paint surface.
In the prior art, the heat-up section has often been provided by radiant ovens. However, radiant ovens have typically not been believed to be capable of providing the hold function. As such, the hold function has almost always been accompanied by large air movement. For that reason, hold zones have typically used convection heating. This belief was due to the difficulty of maintaining a constant temperature across the vehicle with the conventional radiant energy ovens. Radiant ovens that were used in a hold zone were used with large air flow volumes to create turbulent air flow. This defeats the benefit of radiant ovens as described above.